The invention concerns a quick-change coupler for work implements attached to an excavator-beam, a loader arm or similar tool holder. A support-frame (4) is adjustable at the tool-holder and a hook (6) issuing from the support frame and provided with a hook jaw (16) and a free backside and a rest surface (15) is mounted at the support frame behind the hook and a locking means (9). Further, a cross-pipe (21) is mounted to the tool and is associated with the hook jaw and acts as a receiving means. A stop plate (22) cooperates with the rest surface and an intake opening is provided between said stop plate and the cross-pipe whereby, upon a pivoting motion of the support frame, the cross-pipe is seized by the hook jaw and the rest surface (15) is moved against the stop plate (22) and the locking system is actuated.
The British Patent Document GB-A No. 20 40 262 (BEALES STEEL) discloses equipment of the above-stated type which evinces a complex design. A substantial number of pin-means and projections with recesses or clearances must be mutually engaged between the tool holder and the tool before the tool can be locked into the tool holder. When the cross-pins of the tool holder are pressed against the tool to achieve coupling, there is the danger of minor alignment errors such that the tool may roll off. Accordingly, the machine operator encounters substantial difficulties during the receiving procedure.
Similar difficulties are encountered when using the quick-change coupler known from the German Offenlegungsschrift No. 25 13 772 (WAIN-ROY). The pins and the projections are provided at the tool and their associated receiving means, in the form of a hook jaw and a separately arranged hollow are in the tool holder. If the tool is set on uneven terrain or on a slippery foundation, such as gravel or chippings, then the locking at the tool holder requires auxiliary personnel. Excavation includes operations wherein the tool is loaded in all possible directions, including that in which the hook jaw is open. An additional projection means and a receiving means at the tool and the tool holder respectively are provided to absorb the loads in the just-above cited direction. A more complex design, with increased manufacturing costs on one hand and on the other the described coupling problems, necessarily is the result.